"Effects of Extrinsic Rewards on Children's Subsequent Intrinsic Interest" (Green and Lepper, 1974) (<a href="http://www.jstor.org/discover/10.2307/1128110?uid=3737536&uid=2&uid=4&sid=21101686581973" rel="nofollow">http://www.jstor.org/discover/10.2307/1128110?uid=3737536...</a>) and some other papers which came after it showed that introducing extrinsic rewards to what was before a intrinsically motivated activity could actually hurt long-term motivation.<p>I wonder if the same would apply here, if this takes off.